Rehydrate your dry yeast

**Bobby_M** · 03-12-2007, 04:04 PM

In my extract brewing video, I stated that everything I've read suggest rehydrating dry yeast because they hydrate better in water than in high gravity wort. So many people have told me that they pitch their dry yeast right into the wort, no problem. OK, so I wanted to see for myself in case I was wasting the effort. My lag times with the O2 setup and rehydrated dry yeast has been about 6-10 hours.

I checked the dry pitch batch this morning after 12 hours, not bubble one. I'm going back to rehydrating.

AleHole · 03-12-2007, 04:09 PM

My very first batch my LHBS owner told me just to dump it on top of the wort. I did not have an active fermentation for at least 12 hours. Since then I have used rehydrated dry yeast twice and had vigorous fermentation within 8.

**TheJadedDog** · 03-12-2007, 04:19 PM

The main reason for re hydrating is to make sure you have viable yeast. Dry yeast is often older than liquid yeast and since you don't make a starter with it you have no way of knowing if it is any good. The reduced lag time is just a bonus.

**Bobby_M** · 03-12-2007, 04:20 PM

I always check the expiration date on the dry yeast packs. Most of them are nowhere near expired. I guess it just depends where you shop.

sirsloop · 03-12-2007, 04:26 PM

rehydrating takes what... 20 minutes,19 of which are down time while you are going other things like brewing. There's really no reason not to IMHO.

AGBrewer · 03-12-2007, 04:32 PM

I have had the same experience, Yesterday I made a 90 min clone, I rehydrated two packages of safale us56, I had airlock activity within 2 hours. Non-rehydrated brews that I have done have taken up to 2 days to get going, I will rehydrate every time.

zoebisch01 · 03-12-2007, 04:35 PM

One interesting note on rehydrating yeast that I gleaned from the Danstar site was that you should make sure your water is good and clean as the yeast go through a period where they basically are incapable of regulating what is passing through the cell wall. Not sure what this means in terms of practical applications but it is just something to keep in the back of the noodle.

Personally I just follow whatever the manufacturer says. My shortest finished lag time to date was just under 1.5 hrs with T-58. I am talking vigorous airlock activity.

The one thing I don't like is having to sanitize a vessel, water and thermometer to rehdyrate.

**Bobby_M** · 03-12-2007, 04:38 PM

Quote:

Originally Posted by sirsloop

rehydrating takes what... 20 minutes,19 of which are down time while you are going other things like brewing. There's really no reason not to IMHO.

Yeah that's what I figured all along but my brew day was such that shaving off any steps seemed like a great idea. I figure it allowed me to prove it to myself with relatively little harm. Now if this lag turns into a total non start, well what a tough lesson.

**johnsma22** · 03-12-2007, 04:40 PM

I think there is too much emphasis placed on short lag times. Lag time, or more precisely, the adaptive phase of fermentation is when the yeast are in an aerobic state, using up the existing oxygen, taking stock of the nutrients in the wort, and creating the enzymes it needs to adapt to the environment and begin the process of converting the sugars to alcohol and CO2.

A long lag time may only mean that the conditions for yeast growth were ideal and the yeast spent more time increasing there strength and cell count for a more efficient primary fermentation.

Since I have been making starters and using oxygen my lag times have actually increased, but my fermentations have been much more efficient, attenuated better, and the final product has improved immensely.

Check out what John Palmer has to say on the subject of lag times:

Quote:

Originally Posted by John Palmer

It has been common for brewing texts to over-emphasize the "lagtime" - the period of time after pitching the yeast before the foamy head appeared in the fermentor. This lagtime was the benchmark that everyone would use to gage the health of their yeast and the vigor of the fermentation. While it is a notable indicator, the lagtime accounts for a combination of pre-fermentation processes that have a great deal to do with the quality of the total fermentation, but that individually are not well represented by time.

A very short lagtime, for example, does not guarantee an exemplary fermentation and an outstanding beer. A short lagtime only means that initial conditions were favorable for growth and metabolism. It says nothing about the total amount of nutrients in the wort or how the rest of the fermentation will progress.

The latter stages of fermentation may also appear to finish more quickly when in fact the process was not super-efficient, but rather, incomplete. The point is that speed does not necessarily correlate with quality. Of course, under optimal conditions a fermentation would be more efficient and thus take less time. But it is better to pay attention to the fermentation conditions and getting the process right, rather than to a rigid time schedule.

brewt00l · 03-12-2007, 04:41 PM

Quote:

Originally Posted by Bobby_M

I checked the dry pitch batch this morning after 12 hours, not bubble one. I'm going back to rehydrating.

fwiw just to throw some more variables into the mix:

I never rehydrate my dry yeast and haven't had anywhere near a 12 hr lag with dry yeast that I can recall.